Drastic Energy Reduction With gDTX in Low Cost 5G Networks

Base station (BS) sleep modes handle the progressive deactivation of unused hardware components and bring a promising solution to the increasing energy bill and environmental concerns. Taking advantage of the 5G ultra-lean design and spaced synchronization signals, we propose a novel gDTX mode (for next-generation discontinuous transmission), based on flexible duty cycling. First, an inactive period enables the BS to enter deep sleep state for some tens of milliseconds, even if users are requesting service. We show that adapting the inactivity duration to the daily traffic load fluctuations provides significant energy reduction, reaching half of the time more than 45% gain in suburban environment and 78% in rural area. Second, an active period maintains some cell capacity and normal signaling, rendering the BS always available, even if not always on. Questioning the feasibility of gDTX regarding real-time delay-non-tolerant voice traffic, we analyze its impact on the overall jitter, end-to-end delay and estimated mean opinion score. We evidence that sleeping 60 ms every 80 ms while sustaining acceptable voice quality is not contradictory in most network conditions, for light to moderate loads. The proposed gDTX cycle definitely opens new perspectives on energy reduction, targeting primarily developing countries where powering BSs is still a priority to deploy reliable mobile services.